I am installing a beam on a tower and am wondereing what you think is best for a 2" O.D. Mast. 1/4" wall Aluminum Stainless Steel Galvanized Electrical EMT is measured in I.D. not O.D. so that is a problem for 2" O.D. because 2" EMT is more than 2" O.D. 73 Mike, VE4MM